Known apparatus of this type for detecting inclinations or changes thereof in appliances or components thereof is either functionally separated from but mechanically joined to the appliance or such apparatus comprises individual elements of the appliance and its function is coupled to the function of these elements. Designs of the latter type are known from surveying instruments, e.g. levels and theodolites. Such designs are used as compensators to automatically compensate for any deviation of the instrument from its true horizontal position. Such compensations are effected by shifting the position of the image of a target or an optical path for angular measurements by an amount corresponding to the deviation. European patent application EP-A-154 586 (Sercel) discloses such a design wherein a liquid horizon deviates a ray path for angular measurements.
Known inclinometers that operate independently comprise electrooptic means generating electric output signals representing any deviation from level position. U.S. Pat. No. 4,136,955 discloses such an inclinometer joined to a theodolite. If the theodolite deviates from its true horizontal position its electric output signals representing measured angular values are corrected by a microprocessor using the output signals of the inclinometer.
One object of the present invention is to provide an apparatus for measuring inclinations with an improved optical, mechanical and thermal stability and allowing a simple and reproducible mounting to an appliance.